Methylcyclopentene production



Oct. 25, 1949. G. M. GOOD l-:rAL

METHYLCYCLOPENTENE PRODUCTION Filed Sept. 29, 1947 @lli Mvc/Wars: Georye M 60M Patented Oct. 25, 1949 METHYLCYCLOPENTENE PRODUCTION George M. Good, Albany, and Hervey H. Voge, Berkeley, Calif., asslgnors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application september 29, i947, serial No. '176,763

(cl. 26o-.666)

13 Claims;

This invention relates to the production of methylcyclopentenes of high purity. More par- Y ticularly the invention relates to the production of methylcyclopentenes of high purity from complex hydrocarbon mixtures comprising methylcyclopentenes in admixture with close boiling hydrocarbons.

The methylcyclopentenes are valuable as intermediate and starting materials in the production of many valuable chemical derivatives. The need for these unsaturated cyclic compounds, in a state of relatively high purity, has rendered highly desirable suitable means enabling their more eicient production from readily available sources. Sources of the methylcyclopentenes comprise the olenic hydrocarbon mixtures resulting from the thermal or catalytic treatment of naturally occurring or synthetically produced hydrocarbons or carbonaceous materials. The olefinic hydrocarbon mixtures boiling in the motor fuel boiling range obtained, for example, by the catalytic cracking of hydrocarbons, generally contain a substantial amount oi methylcyclopentenes. The complexity of these hydrocarbon mixtures and the presence therein of a multiplicity of hydrocarbons boiling at temperatures in close proximity to the boiling temperatures of the methylcyclopentenes renders extremely diiiicult and often impossible the separation therefrom of these unsaturated 'cyclic hydrocarbons in a relatively high state of purity by methods available heretofore. The complexity of operative steps required, and in some cases the need for the use of catalysts or reagents of relatively high cost, to produce methylcyclopentene of a suilicient degree of purity by methods available heretofore, often render these processes highly impractical as a source of the desired unsaturated cyclic compounds. The difficulty of separating even a single one of the methylcyclopentene isomers from such hydrocarbon mixtures by methods available heretofore is made apparent by a realization of the multiplicity of hydrocarbons having closely approximating boiling temperatures generally present therein. Thus a hydrocarbon fraction consisting essentially of hydrocarbons having six carbon atoms to the molecule and having a boiling range of 65 C. to 69 C., separated from an`olenic cracked gasoline by fractionation will generally contain 3-methylcyclopentene in admixture with the close boiling hydrocarbons indicated in the following table:

2 Table A 2-ethylbutene-1 65 3methylcyclopentene 87 2-methylpentene-2 67 3-methylpentene-2 (trans) 68 Hexene-3 (cis) 68 Hexene-3 (trans) 68 Hexene-2 (cis and trans) 68 n-Hexane 69 A fraction of such unsaturated cracked hydrocarbons boiling in the range of from to 83C. will generally contain 4-methylcyclopentene and 1-methylcyc1opentene in admixture with the close boiling six carbon atom hydrocarbons indicated in the following table:

Table B 0. 3-methylpentene-2 (cis) I1 Methylcyclopentane '72 2,3-dimethylbutene-2 'I3 4-methylcyclopentene 75 l-methylcyclopentene "I6 Methylenecyclopentane 76 Benzene 80 Cyclohexane 81 Cyclohexene 83 Close boiling hydrocarbons other than the six carbon atom 'hydrocarbons are generally encountered which further complicates the problem of separation as evidenced from `the following table of seven carbon atom aliphatic hydrocarbons boiling in therange of from 72 C. to 85 C. encountered in oleiinic cracked gasolinas.

'lhe relatively wide spread in boiling range of the three methylcyclopentene isomers and the fact that the practicality of a process for the production of'relatively pure methylcyclopentenes is often dependent upon a recovery of at least vthe greater part of alll three, renders the use of processes involving such steps as fractionation and olefin extraction, as utilized heretofore, highly unsatisfactory. v

It is an object of the present invention to provide an improved process for the more efiicient production of methylcyclopentenes in a relatively high state of purity from olenic hydnocarbon mixtures comprising methylcyclopentene in admixture with close boiling hydrocarbons inseparable therefrom on a practical scale by methods available heretofore.

Another object of the invention is the provision of an improved process for the more eiiicient production of methylcyclopentene of high purity from olenic cracked hydrocarbon distillates.

A more particular object of the invention is the provision of an improved process for the more efiicient production of methylcyclopentenes consisting essentially of 1-methylcyclopentene and 4-methylcyclopentene of relatively high purity from olenic hydrocarbon fractions comprising 3-methy1cyclopentene. t

A still more particular object of the invention is the provision of an improved process for the recovery of substantially all of the methylcyclopentenes comprised in a hydrocarbon mixture comprising 1, 3, and 4-methylcyclopentenes in admixture with close boiling open chain hydrocarbons in the form of 1- and 4-methy1cyclopentenes of high purity.

Still another object of the invention is the provision of an improved process for the more efficient production of 3-methylcyclopentene of high purity from oleiinic hydrocarbon fractions comprising 1methylcyclopentene and 4-methylcyclopentene. Other objects and advantages of the invention will become apparent from the following detailed description thereof. A

In accordance with the process of the invention methylcyclopentenes are produced from complex olefinic hydrocarbon mixtures comprising methylcyclopentenes in admixture with close boiling aliphatic hydrocarbons, with recovery of at least the greater part of said methylcyclopentenes in a high state of purity, by separating from said hydrocarbon mixture a hydrocarbon fraction comprising S-methylcyclopentene and a hydro` carbon` fraction comprising l-methylcyclopentene and 4-methylcyclopentene, and separately treating said fractions under the conditions defined fully herein to recover at least a substantial part of the methylcyclopentene content therefrom.

The objects and advantages of the invention are obtained by fractionating a complex oleiinic hydrocarbon mixture comprising methylcyclopentenes in admixture with close boiling aliphatic hydrocarbons from any suitable source, such as, for example, a catalytically crackedv gasoline, to separate therefrom a lower boiling hydrocarbon fraction comprising 3methylcyclopentene in admixture With close boiling aliphatic hydrocarbons having six carbon atoms to the molecule, and a higher boiling hydrocarbon fraction comprising l-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling aliphatic hydrocarbons having seven carbon atoms to the molecule. The lower boiling hydrocarbon fraction is subjected to olefin isomerizing conditions effecting the conversion of 3-methylcyclopentene to cyclic oleilns comprising 1-methylcyclopentene and 4inethylcyclopentene. The higher boiling hydrocarbon fraction is separately subjected to olefin isomerizing conditions eflecting'the conversion of l-methylcyclopentene and 4-methylcyclopentene to cyclic olens comprising 3-methylcyclopentene. Methylcyclopentenes in a high state of purity are separated from the products of the isomerization operations.

Of the methylcyclopentenes the tertiary cyclic olefin, l-methylcyclopentene, is often of particular value as vstarting or intermediate material in the production of chemical derivatives therefrom. In a preferred modification of the invention substantially the entire methylcyclopentene content of the complex hydrocarbon mixture charged is recovered as` methylcyclopentenes of high purity consisting essentially only of 1- and 4-methylcyclopentenes. In the modification of the invention the 3-methylcyclopentene produced in the treatment of the higher boiling 1- and 4-methylcyclopentene-containing fraction of the charge, now free of any substantial amount of open chain hydrocarbons, is combined with the lower boiling fraction of the charge to be subjected to the olen isomerizing treatment therewith. In this wise the 3-methy1cyclopentene emanating from the treatment of the higher boiling fraction of the charge is converted, together with the S-methylcyclopentene content of the charge to the system, to 1- and 4-methylcyclopentenes of high purity free of any substantial amount of close boiling open chain hydrocarbons.

I'he process of the invention is applied to the separation of methylcyclopentenes in a high state of purity from complex hydrocarbon mixtures comprising them in admixture with close boiling aliphatic hydrocarbons obtained from any suitable source. Thus the charge to the system may comprise the methylcyclopentene-containing hydrocarbon mixtures obtained in the thermal or catalytic treatment of hydrocarbons, such as, for example, the methylcyclopentene-containing hydrocarbon mixtures obtained in the thermal and catalytic cracking, dehydrogenation, destructive dehydrogenation, reforming, and the like.' of hydrocarbons.

In order to set forth more fully the nature of the invention, it will be described herein with reference to the attached drawing wherein the single figure represents a more or less diagrammatical elevational view of one form of apparatus suitable for executing the process of the invention.

Referring to the drawing, a complex olenic hydrocarbon mixture comprising methylcyclopentenes in admixture with close boiling aliphatic hydrocarbons, such as, for example, a catalytically cracked gasoline, taken from an outside source is forced through valved line I0 into a feed fractionating zone. In the feed fractionating zone, the hydrocarbon charge is fractionated to separate therefrom a lower boiling fraction comprising 3-methylcyclopentene in admixture with close boiling aliphatic hydrocarbons, and a higher boiling fraction comprising l-methylcyclopentene and 4methylcyclopentene in admixturel with close boiling aliphatic hydrocarbons. The feed fractionating zone is indicated in the drawing by fractionators Il, I2, I3 and Il. Within fractionator II a vapor fraction comprising hydrocarbons boiling below about 66 C. is separated as a vapor fraction from a liquid fraction comprising hydrocarbons boiling above about 66 C. The liquid fraction is passed from fractionator H through line` I8 into fractionator l2. Within fractionator I2 a fraction comprising substantially all of the methylcyclopentene content of the charge, such as, for example, a fraction having a boiling range of from about 66 C. to about 77 C.,-

is separated as a vapor fraction from a liquid fraction comprising hydrocarbons vhigher boiling than about 77 C. The vapor fraction comprising isomeric methylcyclopentenes in admixture with close boiling aliphatic hydrocarbons is passed from fractionator l2 byfmeans of line I1 into a fractionator I3. Within fractionator I3 a vapor fraction comprising 3-methy1cyclopentene in admixture with close boiling hydrocarbons, such as, for example, a fraction boiling in the range of from about 66 C. to about 68 C. is separated as a vapor fraction from a liquid fraction comprising hydrocarbons boiling in the range of about 68 C. to about 77" C. The vapor fraction comprising B-methylcyclopentene is taken overhead from fractionator I3 through line I8 and forms the charge to a rst reaction zone.

The liquid fraction is passed from fractionator I3 through line I9 into fractionator I4. Within fractionator I4 a vapor fraction comprising methylcyclopentane, such as, for example, a fraction boiling in the range of from about 68 C. to 74 C., is separated from a liquid fraction comprising substantially all of the 1methylcy clopentene and 4methylcyclopentene originally present in the charge in admixture with close boiling aliphatic hydrocarbons, such as, for example, a fraction boiling in the range of from about 74 C. to about 77 C. The liquid fraction comprising l-methylcyclopentene and ir-methylcyclopentene is taken from fractionator I4 byv means of line 2D and .forms the charge to a sec-.

ond and separate reaction zone of the process.

The 3methylcyclopentene-containing fraction flowing through line IB will comprise a plurality of open chain olenic hydrocarbons having six carbon atoms to the molecule boiling at, or close to, the boiling temperature of 3-methylcyclopentene and therefore inseparable therefrom on a practical scale by such expedients as fractionation.

The methylcyclopentene-containing fraction is passed from line I8 into a heating zone, such as, for example, an externally heated coil 2| positioned in a furnace structure 22. From heating coil 2I, the heated 3methylcyclopentene fraction is passed through line 23 into a suitable rst reaction zone. The iirst reaction zone may comprise a reaction chamber 24.

A hydrocarbon fraction consisting essentially of 3-methylcyclopentene in admixture with closeboiling aliphatic hydrocarbons may be introduced into line I8 from an outside source by means of 4 valved line 21. Such hydrocarbon fraction introduced into the system by means of line 2l may comprise a part or all of the 3fmethylcyclopentene fraction introduced into the rst reaction zone.

`Within reaction chamber 24, the 3-methylcyclopentene fraction is contacted with an olefin isomerization catalyst at oleiin isomerizing conditions set forth fully below, effecting the conversion of B-methylcyclopentene to unsaturated cyclic olens consisting essentially of l-methylcyclopentene, 4-methylcyclopentene and a minor amount of cyclohexene. Under the isomerizing conditions maintained in reactor 24 at least a substantial part of the six carbon atom open chain oleiins are simultaneously converted to isomeric open chain oleflns boiling below 66 C. Isomerization of the S-methylcyclopentene fraction under these conditions is illustrated by the following example: f

Example I An olefinic hydrocarbon fraction having a boiling range of from about 66 C. to about 68 C.. separated from a catalytically cracked gasoline by fractionation, and having a S-methylcyclopentene content of 40% and an open chain Ca oletlne content of 55% is contacted with a. bauxite catalyst at a temperature of 275 C. and atmosp heric pressure. A conversion of 3-methylcyclopentene to l-methylcyclopentene and 4-methylcyclopentene of 70%, and of open chain olens to olens boiling below 66 C. of 30% is obtained. Only about 1/2% of the S-methylcyclopentene is converted to cyclohexene.

Eilluence from reactor 24 comprising l-methylcyclopentene 4-methylcyclopentene, unconverted S-methylcyclopentene, traces of cyclohexene, and the open chain isomerized and unisomerized six carbon atom olefins, is passed through line 29. provided with suitable cooling vmeans such as. for example, a heat exchanger 30, into a product separating zone. Since the highest boiling non-cyclic Cs olen boils at 73 C., and l-methylcyclopentene, 4-methylcyclopentene, and cyclohexene boil at 75, 76 and 83 C., respectively, the 1- and 4-methylcyclopentenes along with the cyclohexene are readily separated from the reactor eluence by fractionation.

The product separating zone receiving reaction products from line 29 is depicted in the drawing by fractionators 3l and 32. Within fractionator 3I a vapor fraction comprising isomerized open chain olefins boiling below `66 C. is separated from a liquid fraction comprising hydrocarbons boiling above 66 C. The liquid fraction is passed from fractionator 3i through line 34 into a fractionator 32. Within fractionator 32 hydrocarbons comprising l-methylcyclopentene, 4-methylcyclopentene as well as cyclohexene are separated as a liquid fraction from a vapor fraction having a boiling range of about 66 to about 74 C. comprising unconverted 3-methylcyclopentene in admixture with close boiling aliphatic olefins. At least a part of the vapor fraction is recycled from fractionator 32, through line 35, into line I8. Valved line 38 is provided to enable the bleeding of a portion of the recycle stream from the system to avoid an accumulation of saturated hydrocarbons boiling in the boiling range of the recycled stream. Although such bleeding will generally suffice, a portion or -all of the recycle stream may be bypassed through valved line 38 into suitable saturated hydrocarbon removing means such as, for example, an extraction zone depicted in the drawing by extraction column 39 and stripping column 40. Within column 39 recycled hydrocarbons may be contacted with a suitable medium selectively absorbing the olefins. Absorbed oleiins, comprising unconverted B-methylcyclopentene are stripped from the fat absorbing medium in stripper 40 and returned therefrom through valved line 4I into line 35 discharging into line I8.

The liquid fraction comprising 1- and 4- methylcyclopentenes and cyclohexene is passed from fractionator 32 through line 44 into a fractionator 45. Within fractionator 45 a vapor fraction consisting essentially of l-methylcyclopentene and 4-methylcyclopentene in a high state of purity is separated from a liquid fraction comprising cyclohexene formed in the system. The

76 vapor fraction consisting essentially of 1rnethy1` separating zone.

cyclopentene .and 4-methylcyclopentene is taken from fractioiiator 45 through valved line 48 as a final product.

The hydrocarbon fraction comprising 1-methylcyclopentene and 4-methylcyclopentene separated from the charge, passing through line 20 will comprise close boiling heptenes inseparable from these methylcyclopentene isomers by ordinary fractionating means. In accordance with the invention, the hydrocarbon stream owing through line 20 is passed into a heating zone, such as, for example, an externally heated coil 53, positioned in a furnace structure 54. From coil 53 the heated hydrocarbon stream is passed through line 55 to a second reaction zone of the process, such as, for example, a reaction chamber 56.

Additional hydrocarbons from an outside source consisting essentially of 1- and 4-methylcyc1opentenes in admixture with close boiling open chain olefins having seven carbon atoms to the molecule may be introduced into the system by means of valved line 58. Such hydrocarbons additionally introduced through valved line 56 may constitute a part or all of the hydrocarbons comprising 1- and 4-methylcyclopentenes in admixture with close boiling aliphatic hydrocarbons introduced into the system.

Within reactor 56 the hydrocarbon stream is' contacted with an olefin isomerizing catalyst at olefin isomerizing conditions effecting the conversion of l-methylcyclopentene and 4-methylcyc1opentene to cyclic olens consisting of 3-methylcyclopentene and some cyclohexene.

Etliuence from reactor 56 is passed through line 5|, provided with siutable cooling means, such as, l

for example, a heat exchanger 60, into a product The product separating zone receiving eiliuence from reactor 56 is depicted in the drawing by fractionators 62 and 63.

Since the boiling temperature of 3methyl cyclopentene is 67 C. and that of the lowest boiling heptene is 72 C., separation of the 3-methylcyclopentene from the reactor eiliuence is now easily accomplished by conventional fractionating means. Within fractionator 62 a vapor fraction -comprising S-methylcyclopentene is separated from liquid fraction comprising unconverted 1- and 4-methylcyclopentenes in admixture with Aclose boiling heptenes and some cyclohexene.

The vapor fraction consisting essentially of 3- methylcyclopentene is taken overhead from fractionator 62 through valved line 64. The 3-meth- ,ylcyclopentene thus passed through' line 64 may be taken from the system in part or entirety as a inal product, or may be passed through valved line 65 into line 46 to combine with the 1,- and 4-methylcyclopentenes flowing therethrough to obtain a single mixed methylcyclopentene product free of aliphatic hydrocarbon.

The liquid fraction is passed from fractionator 62 through line 61 into fractionator 63. Within fractionator 63 a vapor fraction comprising unconverted 1- and 4-methylcyclopentenes in ad- `mixture with close boiling heptenes and cyclohexene, such as, for example, a fractionV boiling in the range of about 70 to 84 C., is separated as a vapor fraction from a liquid fraction boiling above about 84 C. comprising higher boiling materials including isomeric open chain C7 olens `formed within the system. 'I'he liquid fraction is taken from fractionator 63 through valved line 68 and eliminated from the system. The vapor fraction is recycled from fractionator 63 by means of line 69 into line 20. A valved line 'I0 is proavoidance oi its further formation in any aubstantial amount at the expense @im f methylcyclopentenes in reactor et.

Optionally a part or all of the fraction '1 g to reactor 68 may be subjected to a treatment effecting the removal of at least a oi the paranlns therefrom. To this effect a valved line 14 is provided for the passage of at least a of the hydrocarbon stream from line 26 into a suitable saturated hydrocarbon removing zone. such as, for example, an extraction zone represented in the drawing by extraction column 'Il and stripping column 16. Within column 'l5 the hydrocarbon stream is contacted with a medium having afselective solvent action for olens. The olefinic constituents of the stream, comprising 1- and 4-methylcyclopentenes in admixture with close boiling heptenes are passed from stripper 76 through valved line 'I'l intollne 2li-leg to coil 63. When the hydrocarbon stream introduced into heating coil 63 comprises benzene in substantial amount, these aromatics may optionally be separated therefrom to at least a substantial degree by conventional means not shown in the drawing.

The manner of isomerlzation of the land 4- methylcyclopentene-containing fraction to products 'comprising 3methylcyclopentene in accordance with the process of the invention is illustrated by the following example:

Example II cyclopentene content of the complex hydrocarbon charge to the system as methylcyclopentenes consisting essentially only of 1- and 4-methylcyclopentenes is obtained by passing the 3-methylcyclopentene emanating from reaction chamber 56, from line 64, through valved line 86, into line il. In this wise WeB-methylcyclopentene produced in reaction chamber 66 will again be converted to 1- and 4-methy1cyclopentenes in reactor 26 and eliminated from the system free of any substantial amount ofv open chain hydrocarbons through valved line 46.

As indicated above the boiling range of the methylcyclopentene fractions introduced into the respective isomerizing zones may vary to some degree within the scope of the invention. Thus the higher boiling fraction separated from the charge through valved line 20 may optionally comprise at least a substantial part of the cyclohexene content of the hydrocarbon charge to the feed fractionating zone of the system. Under the conditions maintained in thereactor 66 at least a substantial part of the cyclohexene will undergo conversion therein to methylcyclopentenes thereby materially increasing'the methylcyclopentene production oi' the process.

, 9 Catalyst; employed in reactors 24 and 5l cometc.' These catalytic materials maybe subjected to a pretreatment before use. Such pretreatments comprise, for example, subiectlonto elevated temperatures, optionally in the presence of gaseous materials such as hydrogen, nitrogen, steam, gases comprising them, or the catalysts may be contacted with an inorganic mineral acid such as hydrochloric acid, sulfuric acid, carbamic acid, hydrofluoricacid, boric acid, etc. A particularly preferred type of catalyst comprises adsorptive aluminous materials containing substantial amounts of gamma alumina which has been pretreated with an acidic material. Although adsorptive materials are preferred as catalysts for the isomerization of the methylcyclopentenes, the invention is not necessarily limited thereto and other catalysts capable of activating the olefin isomerization reaction may be employed. Such catalysts comprise for example, catalysts of the type of naturally occurring siliceous materials such as clays, bentonites, or the like, aluminasilica compounds or mixtures thereof; zeolites;

oxides of Be, Si, Ti, Th, V, Zr, Mn; etc. Other .suitable catalysts are those comprising phosphoric acid and silica, as well as any acid of low volatility preferably on a solid oxide support material. Of the isomerization catalysts, those consisting essentially of alumina are somewhat preferred.

Temperatures within reactors 24 and 56 are maintained in the range of fromabout 150 to about 650 C., and preferably from about 200 to about 350 C. Temperature conditions in reactors 24 and 56 are controlled by the heat input into the hydrocarbon streams flowing through externally heated coils 2l and 53, respectively. The isomerization reactions are preferably executed in the vapor phase. Atmospheric, or superatmospheric pressures may be maintained within reactors 24 and 56. Pressures close to atmospheric have been found satisfactory. Throughput rates in terms of a liquid hourly space velocity of, for example, from about 0.5 to about 25 are employed.

Under the above-defined conditions 3-methylcyclopentene is converted to cyclic olens consisting predominantly of 1- and 4-methylcyclopentenes in reactor 24; and 1- and 4- methylcyclopentenes are converted to cyclic olefins consisting essentially of 3-methylcyclopentene in reactor 56. .Formation of undesirable by-products due to side reactions such as hydrocarbon degradation and polymerization are readily maintained at a minimum. Formation of the desired methylcyclopentenes with a minimum formation of cyclohexene is favored by the avoidance of relatively severe isomerization conditionsin reactors 24 and 56. Mild isomerization conditions are obtained by 'the use of the lower temperatures within the prescribed temperature ranges and of the less active isomerization catalysts. Thus catalysts suitable for use under such mild isomerization conditions comprise such catalysts as phosphoric acid, and bauxite. Formation of cyclohexene in reactor 56 is further suppressed, as indicated above, by the recycling of cyclohexene to the reaction zone.

For the purpose of clarity, all parts of apparatus not essential to a complete description of the invention comprising, `for example. lpumps, condensers, completel fractionating systems, accumulators, etc., have been omitted from the drawing. It is to be understood that the apparatus shown maybe modified as apparent to one skilled in the art without departing from the scope of the invention.

The invention claimed is:

1. The process for the production of methylcyclopentenes in a relatively high state of purity from complex hydrocarbon mixtures comprising i-methylcyclopentene, 3-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six and seven carbon atoms to the molecule inseparable therefrom by fractionation o'n a practical scale, which comprises separating a lower boiling fraction comprising 3-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six carbon atoms to the molecule and a higher boiling fraction comprising l-methylcyclopentene and ii-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having seven carbon atoms to the molecule from said hydrocarbons mixture, contacting said lower boiling fraction with a solid adsorptive laluminous material under olefin isomerizing conditions at a temperature of from about 200 C. to about 350 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of 3-methylcyclopentene to 1-methylcyclopentene and 4methylcyclopentene in a first reaction zone, separately contacting said higher boiling fraction with a solid adsorptive aluminous material under oleiln isomerizing conditions at a temperature of from about 200 C. to about 350 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of 1methy1cyclopentene and 4-methylcyclopentene to S-methylcyclopentene in a, second reaction zone, fractionating l-methylcyclopentene and 4-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbonsA from the eilluence of the first reaction zone, fractionating B-methylcyclopentene -free of any substantial amount of open chain aliphatic hydrocarbons from the eilluence of the second reaction zone, and combining said 3-methylcyclopentene fractionated from the eiiluence of said second reaction zone with said 1- and 4-methylcyclopentenes fractionated from the eilluence of said rst reaction zone to obtain a mixture of isomeric methylcyclopentenes of high purity.

2. The process for the production of methylcyclopentenes in a relatively high state of purityI from complex hydrocarbon mixtures comprising l-methylcyclopentene, 3-methylcyclopentene and 4-methylcyclopentene in admixture with `close boiling open chain aliphatic hydrocarbons having six and seven carbon atoms to the molecule inseparable therefrom by fractionation on a practical scale, which comprises separating a lower boiling fraction comprising 3-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six carbon atoms to the molecule anda higher boiling fraction comprising l-methylcyclopentene and 4methylcyclo pentene in admixture with close boiling open chain aliphatic hydrocarbons having seven carbon atoms to the molecule from said hydrocarbon mixture, contacting said lower boiling fraction with a solid isomerization catalyst comprising adsorptive alumina under olefin isomerizing conconversionof 3-methylcyclopentene to l-methylcyclopentene and 4-methylcyclopentene in a first reaction zone, separately contacting said higher boiling fraction with a solidrisomerization catalyst comprising adsorptive alumina under oleiin isomerizing conditions at a temperature of from about 200 C. to about 350 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of l-methylcyclopentene and 4-methylcyclopentene to 3-methylcyclopentene in a second reaction zone, fractionating 1methylcyclopentene and 4-meth'ylcyclopentene free of any substantial vamount of open chain aliphatic hydrocarbons from the eiliuence of the first reaction zone, Vfractionating B-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eiiluence of the second reaction zone, and combining said 3-methylcyclopentene fractionated from the eiiiuence of said second reaction zone with said 1- and'fi-methylcyclopentenes fractionated from the eiluence of said first reaction zone to obtain a mixture of isomeric methylcyclopentenes l of high purity.

3. The process for the production of methylcyclopentenes in a relatively high state of purity from complex hydrocarbon mixtures comprising 1methylcyclopentene, 3-methy1cyclopentene and 4methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six and seven carbon atoms to the molecule inseparable therefrom by fractionation on a practical scale which comprises separating a lower boiling fra-ction comprising 3-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six carbon atoms to the molecule and a higher boiling fraction comprising l-methylcyclopentene and 4methyloyclo pentene in admixture with close boiling open chain aliphatic hydrocarbons having seven carbon atoms to the molecule from said hydrocarbon mixture', contacting said lower boiling fraction with a solid olefin isomerizing catalyst under olefin isomerizing conditions at a temperature of from about 150 C. to about 650 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby'eecting the conversion of 3-methylcyclopentene to l-methylcyclopentene and 4- methylcyclopentene in a first reaction zone, separately contacting said higher boiling fraction with a solid olen isomerizing catalyst under olefin isomerizing conditions at a temperature of from about 150 C. to about 650. space velocity of from about 0.5 to about 25 thereby effecting the conversion of l-methylcyclopentene and 4-methylcyclopentene to 3methyl cyclopentene in a second reaction zone, fractionating 1-methylcyclopentene and 4-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eiiluence of the first reaction zone, fractionating B-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eiliuence of the second reaction zone, and combining said 3-methylcyclopentene fractionated from the eiiiuence of said second reaction zone with said 1- and 4-methylcyclopentenes fractionated from the eilluence of said first reaction zone to obtain a mixture of isomeric methylcyclopentenes of high purity.

4. The process for the production of methylcyclopentenes in a relatively high state of purity C. and a liquid hourly l `12 from complex hydrocarbon fractions comprising l-methylcyclopentene.' 3methylcyclopente`ne-and 4-methylcyolopente`ne inl admixture with clleg boiling open chain aliphatic hydrocarbons having f six. and seven 'carbon atoms to the molecule inseparable therefrom by fractionation on a practical scale, which comprises separating a lower boiling fraction comprising 3methylcyclopentene win admixture with close boiling open chain-aliphatic hydrocarbons having six carbon atoms to the molecule and a higher boiling fraction comprising l-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having seven carbon atoms to the molecule from said -hydrocarl`-` fractions, contacting said lower boiling fraction with a solid isomerization catalyst comprising adsorptive alumina under olefin isomerizing conditions at a temperature of from about (i.` to about 650 C. and a liquid hourly space velocityof from about 0.5 to about 25 thei'`A """w the conversion of 3-methylcyclopentene to methylcyclopentene and 4methylcyclopentene in a first reaction zone, separately contacting said higher boiling fraction with a solid isomerization catalyst comprising'y adsorptive alumina under olen isomerizing conditions at a temperature of from about 150 C. to about 650 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of i-methylcyclopentene and 4-methylcyclopentene to 3- methylcyclopentene in a second reaction zone, fractionating 1methylcyclopentene and 4-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eilluence of the first reaction zone, fractionating 3-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eiliuence of the second reaction zone, and combining said 3-methylcyclopentene fractionated from the leifluence of said second reaction zone with said 1- and 4-methylcyolopentenes fractionated from the eiiiuence of said first reaction zone to obtain a mixture of isomeric methylcyclopentenes of high purity.

5. The process for the production of methylcyclopentenes in a relatively high stato of purity from cracked gasoline comprising l-methylcyolopentene, 3-methylcyclopentene and 4methyl cyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six and seven carbon atoms to the molecule inseparable therefrom by fractionation on a practical scale, which comprises separating a lower boiling fraction comprising 3-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six carbon atoms to the molecule and a higher' boiling fraction comprising lmethylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having seven carbon atoms to the molecule from said cracked gasoline, contacting said lower boiling fraction with a solid isomerization catalyst comprising adsorptive alumina under olefin isomerizing conditions at a temperature of from about 150 C. to about 650 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of 3-methylcyclopentene to l-methylcyclopentene and 4-m^-^vnlopentene in a first reaction zone, separately cv... boiling fraction with a solid isomerization catalyst comprising adsorptive alumina under olen isomerizing conditions at a temperature of from about 150 C. to about 650 C. and a liquid hourly assuma tene and i-methylcyclopentene to 3-methylcyclo pentene in a second reaction zone. fractionating l-methylcyclopentene and i-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eiiiuence of the first reaction zone, fractionating 3-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eiiiuence of the second reaction z6ne,'and combiningvsaid 3-methylcyclopentene fractionated from the effluence of said second reaction zone with said 1- and i-methylcyclopentenes fractionated from the eilluence of said first reaction zone to obtain a mixture of isomeric methylcyclopentenes of high purity.

6. The process for the production of methylcyclopentenes in a relatively high state of purity from cracked gasolines comprising 1-methylcyclopentene, 3-methylcyclopentene and 4meth ylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six and seven carbon atoms to the molecule inseparable therefrom by fractionation on a practical scale, which comprises separating a methylcyclopentene-containing fraction having a boiling range of from about 66 C. to about 77 C. from said gasoline, separating a lower boiling fraction boiling in the range of from about 68 C. to about 68 C. comprising 3-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six carbon atoms to the molecule and a higher boiling fraction having a boiling range of from about 74 C. to about 77 C. comprising 1-methylcyclopentene and it-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having seven carbon atoms to the molecule from said'methylcyclopentene-containing fraction, contacting said lower boiling fraction with a solid olefin isomerizing catalyst under olefin isomerizing conditions at a temperature of from about 200 C. to about 350 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of S-methylcyclopentene to 1-methylcyclopentene and 4-methylcyclopentene in a first reaction zone, separately contacting said higher boiling fraction with a solid olefin isomerizing catalyst under olefin isomerizing conditions at a temperature of from about 200 C. to about 350 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of 1methylcyclopentene and 4-methylcyclopentene to 3-methylcyclopentene in a second reaction zone, fractionating l-methylcyclopentene and 4-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the emuence of the first reaction zone, fractionating 3-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eiiiuence of the second reaction zone, and combining said 3-methylcyclopentene fractionated from the eiiluence of said second reaction zone with said' 1- and 4-methylcyclopentenes fractionated from the eflluence of said first reaction zone to obtain a mixture of isomeric methylcyclopentenes of high purity.

7. The process for the production of methylcyclopentenes consisting essentially only of 1- and 4-methylcyclopentenes in a relatively high state of purity from complex hydrocarbon mixtures comprising l-methylcyclopentene, 3-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocar- 14 bons having six and seven carbon atoms to the molecule inseparable therefrom by fractionation on a practical scalewhich comprises separating a lower boiling fraction comprising S-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having six carbon atoms to the molecule and a higher boiling fraction comprising 1-methylcyclopentene and 4- methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons having seven carbon atoms to the molecule from said hydrocarbon mixture, contacting said-lower boiling fraction with a solid olefin isomerizing catalyst under olefin isomerizing conditions at a temperature of from aboutv 150 C. to about 650 C. and a liquid hourly space velocity of from about 0.5 to about 25 'thereby effecting the conversion of 3-methylcyclopentene to l-methylcyclopentene and 4-methylcyclopentene in a first reaction zone, separately contacting said higher boiling fraction with a solid olefin isomerizing catalyst under olefin isomerizing conditions at a temperature of from about 150 C. to about 650. C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of l-methylcyclopentene and 4-methylcyclopentene to 3- methylcyclopentene in a. second reaction zone. fractionating -methylcyclopentene free of any g substantial amount of open chain aliphatic hydrocarbons from the eflluence of the second reaction zone, passing said S-methylcyclopentenes fractionated from the elliuence of the second reaction zone to said first reaction zone, and fractionating 1-methylcyclopentene and 4-methylcyclopentene free of any substantial amount oi' open chain aliphatic hydrocarbons from the efiiuence of the first reaction zone.

8. The process for the production of methylcyclopentenes consisting essentially of 1-methylcyclopentene and 4-methylcyclopentene in a relatively high state of purity from cracked gasoline comprising 1-methylcyclopentene, 3-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons inseparable therefrom by fractionation 'on a practical scale, which comprises separating from said gasoline a fraction comprising 3-methylcyclopentene in admixture with close boilingopen chain aliphatic hydrocarbons, contacting said fraction comprising 3-methylcyclopentene with a solid adsorptive aluminous material under olefin isomerizing 'conditions at a temperature of from about 200 C. to about 350 C. and a liquid hourly space velocity of from .about 0.5 to about 25 thereby effecting the conversion of 3- methylcyclopentene to methylcyclopentenes consisting essentially of l-methylcyclopentene and 4-methylcyclopentene in reaction zone, and fracltionating methylcyclopentenes consisting essentially of l-methylcyclopentene and 4-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the efiiuence of said reaction zone.

9. 'I'he process for the production of methylcyclopentenes consisting essentially of I-methylcyclopentene and 4-methylcyclopentene in a. relatively high state of purity from a cracked gasoline fraction comprising l-methylcyclopentene, 3- methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons inseparable therefrom by fractionation on a practical scale, which comprises separating from said cracked gasoline fraction, a fraction comprising S-methylcyclopentene in admixture with close boiling open chain aliphatic hydromethylcyclopentene with a solid oleiin isomerizing catalyst consisting essentially ofadsorptive aluany substantial amount of open chain aliphatic mina under olen isomerizing conditions at a temperature of from about 150 C. to about 650 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of 3methylcyclopentene to methylcyclopentenes consisting essentiallyl of 1methylcyclopentene and 4-methylcyclopentene in a reaction zone, and

fractionating methylcyclopentenes consisting essentially of l-methylcyclopentene and 4-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the ein ence of said-reaction zone.v

10. The process for the production of methylcyclopentenes consisting essentially of 1methyl cyclopentene and 4-methylcyclopentene in a relatively high state of purity from a hydrocarbon mixture comprising l-methylcyclopentene, 3- methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons inseparable therefrom by fractionation on a practical scale, which comprises separating from said hydrocarbon mixture a fraction comprising 3methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons, contacting said fraction comprising 3- methylcyclopentene with a solid olen isomerizing catalyst under olefin isomerizing conditions at a temperature of from about 150 C. to about 650 C. and a liquid hourly space velocity of from about 0.5 to aboutthereby effecting the conversion of 3-methylcyclopentene to methylcyclopentenes consisting essentially of l-methylcyclopentene and 4-methylcyclopentene in a reaction zone, and

fractionating methylcyclopentenesconsisting essentially of l-methylcyclopentene and 4-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the efliuence of said reaction zone.

11. The process for the production of B-methylcyclopentene in a relatively high state-of purity from cracked gasoline comprising 3-methylcyclopentene, 4-methylcyclopentene and 1methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons inseparable therefrom on a practical scale by fractionation, which comprises separating from said gasoline a fraction comprising l-methylcyclopentene and 4- methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons, contacting said fraction with a solid adsorptive aluminous material under olefin isomerizing conditions at a temperature of from about 200 C. to about 350 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of 1methylcyclopentene and 4-methylcyclopentene to S-methylcyclopentene in a reaction zone,A and fractionating .3-methylcyclopentene free of hydrocarbons from the eiiluence of said reaction zone.

12. The process for the production of 3-methylcyclopentene in a relatively high state of purity from a cracked gasoline fraction comprising 3-methylcyclopentene, 4-methylcyclopentene and l-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons inseparable therefrom on apractical scale by fractionation, which comprises separating from said gasoline fraction, a fraction comprising l-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons, contacting said fraction comprising 1-methylcyclopentene and 4-methylcyclopentene with a solid olefin isomerizing catalyst consisting essentially of adsorptive alumina under olen isomerizing conditions at a temperature of from about C. to about 650 C. and a liquid hourly space velocity of from about 0.5 to about 25 thereby effecting the conversion of l-methylcyclopentene and 4-methylcyclopentene to 3- methylcyclopentene in a reaction zone, and fractionating 3- methylcyc1opentene free of any substantial amount of open chain aliphatic hydrocarbons from the efiiuence of said reaction zone.

13. The process for the production of 3-methylcyclopentene in a relatively highstate of purity from a hydrocarbon mixture comprising 3- methylcyclopentene, 4-methylcyclopentene and .l-methylcyclopentene in admixture with close boiling open chain aliphatic hydrocarbons inseparable therefrom on a practical scale by fractionation, which comprises separating from said hydrocarbon mixture a fraction comprising 1- methylcyclopentene and 4-methylcyclopentene in yadmixture with close boiling open chain aliphatic pentene in a reaction zone, and fractionating 3-methylcyclopentene free of any substantial amount of open chain aliphatic hydrocarbons from the eiiiuence of said reaction zone.

GEORGE M. GOOD. HERVEY H. VOGE.

REFERENCES CITED The following references are of record in the file of this patent:

Plate, J. Gen. Chem. (U. (1945).

Arbuzov et al., Compt. Rend. (U. S. S. R.) 30,- 717-20 (1941).

S. S. R'.) 15, 156-64 

